Key Takeaways
- The October 4 disaster in Sikkim was triggered by a moraine collapse at South Lhonak Lake.
- Overflow from the lake flooded the Teesta river, causing widespread damage and missing persons.
- Satellite monitoring, especially Sentinel‑2 imagery, is tracking the lake’s water level and moraine stability.
Gangtok: The October 4 disaster in Sikkim, caused by the overflow of South Lhonak Lake, killed scores of people.
The event is being closely monitored using various satellite data, according to a Sikkim government communique released on Monday.
” As per the interpretation of the available images (Sentinel 2: 6″ October 2023, 4.36 pm), the Department of Science and Technology (state), has preliminarily inferred that there has been a detachment of the
side wall (north west side) of the lateral moraine (rocks and debris) of the South Lhonak Lake (North Sikkim),
measuring approximately 600m length x 225m height x 150m width from the surface level of the lake. As per the data available, the moraine eventually plunged into the lake.” the communique said.
The detached moraine fell and pushed into the deepest portion of the lake resulting in overflow of a large volume of water from the outlet, which led to widening and deepening at the outlet of the lake and flooding the mighty Teesta river.
The image also depicted the decrease in water level of the lake as a large volume of water has spilled over. The area of the lake has decreased from 162 hectare to 144 hectare. However, during this entire sequence of events, it has been observed as per the data available that the main moraine damming the lake, remains in its original position and shape, the statement added.
